Superabsorbent materials are known to be useful in products intended to absorb liquids. These materials are most often found in powder or particulate form and have in the past been incorporated into laminates and/or nonwoven fibrous webs so they would be in a form that is easy to handle in high speed manufacturing processes. These laminates and/or webs are also useful for keeping the powder/particulates fixed in the absorbent structure. For example, U.S. Pat. No. 3,686,024, issued Aug. 22, 1972, to Nankee, et al., describes a water absorbent coated article which contains a fibrous support such as, for example, a fabric or a paper backing and a water insoluble polymer. According to the patent, the coated article is made by impressing the water insoluble polymer upon the substrate while the polymer is in the form of a gel substantially swollen with water. U.S. Pat. No. 4,096,312, issued Jun. 20, 1978, to Holst, et al., describes a hydrophilic support web which has been coated with modified cellulose ether. According to the patent, a hydrophilic web such as a tissue or paper web is wetted with water and then coated with crushed or powdered modified cellulose ether and then dried. The U.S. Pat. No. 4,260,443, issued Apr. 7, 1981, to Lindsay, et al., discloses a laminate of tissue-like materials which are Separated by a layer of liquid absorbing material. According to the patent, a dry liquid absorbing material is applied to a first sheet. A second water permeable sheet is superposed on the first sheet. Water is applied to portions of the second sheet to moisten the liquid absorbing material and cause it to serve as an adhesive which bonds the first and second sheets together.
Latex binders, thermoplastic adhesive resins and thermoplastic adhesive films are also disclosed as useful for attaching absorbent materials to a substrate. For example, U.S. Pat. No. 4,392,908, issued Jul. 12, 1983, to Dehnel, discloses a process for making absorbent articles by attaching water soluble particles to a substrate using a thermoplastic adhesive resin. U.S. Pat. No. 4,600,462, issued Jul. 15, 1986, to Watt, discloses an absorbent web which is made by bonding a nonwoven web with an adhesive material, curing the adhesive material, and then coating the treated web with a solution of a water soluble hydrophilic material and drying the web. U.S. Pat. No. 4,675,209, issued Jun. 23, 1987, to Pedigrew, discloses an absorbent composite in which a melt adhesive film is used to affix absorbent particles to a substrate.
Also disclosed are absorbent composites which are made by depositing dried absorbent particles on to a moistened paper or tissue layer or wet laid fibrous web. For example, U.S. Pat. No. 4,851,069, issued Jul. 25, 1989, to Packard, et al., discloses a laminate of tissues enclosing an intermediate layer of absorbent particles. According to the patent, the absorbent particles are applied to the moistened surface of one of the tissue layers. A second tissue layer is superposed on the first tissue/particle layer and the assembly is then bonded together using heat and pressure. European Patent Publication 0359615-A1, published Mar. 21, 1990, describes a superabsorbent composite structure which is made by depositing dry solid superabsorbents directly on a wet laid web of cellulosic fibers prior to drying the wet laid web.
Although these references describe various absorbent structures, they still fail to address problems associated with distributing liquid throughout a structure containing superabsorbent materials to make efficient use of all the superabsorbent materials. When superabsorbent materials are added to nonwoven webs or incorporated into laminates, they generally appear to reduce the liquid distribution properties of those webs or laminates. Thus, there is still a need for an improved absorbent structure which combines desirable liquid absorption/retention properties with desirable liquid distribution properties.